Reversal process of color photography



1941- L. D. MANNES ET AL 2,252,718

REVERSAL PROCESS OF COLOR PHOTOGRAPHY Filed Jan. 19, 1938 Fig.1.

EXPOSED BL [1E GREEN RIJ'D GREEN sENs/ E AFTER ToR LAYER EXPOSURE 525,? AND YELLOW DEVELOPMENT 14E TER NEGATIVE DE I/EL OPMEN AFTER REMOWIL 0/ S/Ll/EI? AND YELLOW FILTER v 4 EXPOSED RED LIGHT 1 WTER BOTTOM LAYER EXPOSURE F g B, HAND BLUE-GREEN DEVELOPMENT EXP05ED- WH/TEL/GHT 15 15 EXPOSED- WHITE LIGHT 10 15 17 L AFTER MIDDLE Z0 LAYER EXP05URE I AND MAGENTA l9 Sty DEvELoRMENT Leopold D. Mannes f 16 Leopold Godowsky, Jr; 1

W Lot 5. Wllder INVENTORS ATTORNEYS Patented Aug. 19, 1941 I UNITED STATES PATENT orrlce REVERSAL PROCESS OF COLOR PHOTOGRAPHY Leopold D. Mannes, Leopold Godowsky, Jr., and Lot S. Wilder, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application January 19, 1938, Serial No. 185,700

In Great Britain November 19, 193'! 6 Claims.

This invention relates to color photography and particularly to a process of producing colored photographic images in multilayer film.

In processes of three-color photography in which the three color-separation images are formed in separate films or in which two of the images are formed in one film and the third on another film, relatively simple and straightforward methods of processing may be used. It is more desirable to have the three layers, used to record the photographic image, superposed on the same side of a single photographic support in order to secure perfect registration of the images, avoid the necessity of complicated camera structures, and secure better color rendition. Films in which the three layers are superposed on the same side of a single support require carefully regulated and somewhat complicated processing steps in order to obtain images of different colors in the three layers. A process of this type is described in British Patent No. 440,032, filed February 27, 1935 by. two of the present applicants.

Other related color processes in which multilayer or monopack film has been used and images formed therein by reversal processes have been disclosed in the United States patents of Seymour, No. 1,900,870, granted March 7, 1933 and 1,897,866 granted February 14, 1933 and Capstaif No. 1,954,346, granted April 10, 1934.

It has been supposed hitherto that, in a reversal process such as those described in the above patents, the re-exposure of the layers must be to completely uniform light and that the exposure of one layer through another layer containing a developed image will necessarily impress that image upon the layer being exposed. We have found, however, that if there is formed in one of the outer layers, a negative image of silver and a complementary positive image of silver and dye, a lower layer may be printed through this with substantially uniform exposure.

Of course, the exposure must be rather long because of the density of the images, but it will not be impractically long, since the component layers are extremely thin and the fully developed est the support.

It is an object of the present invention to simplify by the above means the methods for producing colored images in three layer photographic film. A further object is to provide a novel method for producing colored photographic reversal images in three colors by color forming development steps. A still further object is to provide a reversal process in which the necessity of bleaching a dye formed in a photographic layer is avoided and the number of processing steps necessary to obtain a multi-color image is reduced.

These and other objects are accomplished by successively exposing and developing the separate layers of a multi-layer film, the exposure being carried out so that only a single layer of the film is exposed prior to each color development step. In the accompanying drawing which forms part of the present invention, Fig. 1 shows six enlarged sectional views of a three-layer film showing the processing steps of the preferred embodiment of our invention and Fig. 2 is an enlarged sectional view of a film used according to our invention showing the antihalation layer therein.

The preferred form of sensitive element used according to our invention is a three-layer film comprising a support ll! of transparent material such as glass, cellulosic material such as cellulose nitrate, cellulose acetate, cellulose acetate propionate, or a suitable synthetic resin, coated with the silver halide emulsion layers ll, l2 and I3 sensitive respectively to the red, green and blue regions of the spectrum. The layers II and I2 are also sensitive to the blue region of the spectrum and it is, therefore, necessary to protect them from the action of blue light during the exposure. This is accomplished by coating a thin gelatin layer I4 containing a yellow dye between the layers l2 and I3. Agelatin layer I5 is also coated between the red and green sensitive layers II and I2. Although the layers l4 and I5 are used according to the preferred embodiment of our invention, they are not absolutely essential and may be omitted. The yellow filter material contained in the layer It may be incorporated in the blue sensitive layer I3.

' velopment, will appear as shown in the second stage of Fig. 1. As shown therein, the layers II, I! and 13 contain, respectively, images It,

formed by this development.

l1 and iii of metallic silver representing the red, green and blue bands of exposing light. images shown in the second stage of Fig. 1 are produced by development by familiar baths, as for 10 minutes at 20 C. in a developer which may have the following composition:

After washing the film for about minutes, it is exposed through the base for about 20 seconds to 100 ft. candles of light through a red filter, transmitting light of longer wave-length than 6400 A. U. to expose the bottom layer II. No intermediate drying step is necessary'at this stage.

After exposure in this way, the film is developed for 12 minutes in a color-forming developer which may have the following composition:

Solution A Grams p-Amino diethylaniline hydrochloride 2 Sodium sulfite 6 Sodium carbonate 50 Potassium bromide 5 Potassium thiocyanate 1 Water to 950 cc.

Solution B o-Hyroxy diphenyl grams 3 Sodium hydroxide do 5 Water .cc 50 (Solution B is added to Solution A) The film is then washed for a few minutes.

After treatment in the above way, the film contains a blue green positive image if! in the bottom layer as shown in the third stage of Fig. 1. The image IS in addition to containing a blue green dye formed by the color development step, also contains the metallic silver The bottom layer 5 i, therefore, contains a blue-green and metallic silver positive image I9. and the metallic silver negative image 16. The layers I2 and. i3 are unafiected and still contain sensitive silver halide grains.

The film is then exposed from the support side to green or white light of an intensity of from 2000 to 13,000 foot candles for about 20 seconds. This exposure affects only the middle layer l2 of the film since the yellow filter layer I4 which re: mains in the film at this stage absorbs any blue light which would otherwise affect the sensitive layer [3. This exposure is of sufficient intensity to expose the emulsion residue of the middle layer completely. The green sensitivity of this layer may have diminished or have been destroyed by this time, in which event, it is preferable to use white light exposure at this stage. This exposure is made through the combined negative and positive images now existing in the low layer which has a generally high overall density. Small differences in this density.

due to either the negative or positive image having a higher gamma than the other do not affect the exposure of the middle layer differentially The since this exposure is made, sufilciently high on the sensitivity curve of the residual emulsion to allow for small diiierences in the intensity of the printed light over diiierent areas of the film.

The fihn is then developed in a magenta colorforming developer after which it appears as shown in the fourth stage of Fig. 1 withithe blue, green and silver positive image in the bottom layer and a magenta and silver positive image 20 in the intermediate layer. The top layer 13 retains its light sensitivity. The film also retains at this stage the negative images l6, l1 and I8.

To obtain the magenta image, the fihn is developed for about 10 minutes in a developer which may have the following composition:

Solution A Grams p-Amino diethylaniline hydrochloride 1 Sodium sulfite 1 Potassium bromide '2 Water to 950 cc.

' Solution B 1-phenyl-3-methyl pyrazolone grams 3 Sodium hydroxide dO 3 Water cc-.. 50

(Solution B is added to Solution A) After development the film is washed for five minutes.

The film is then exposed from the emulsion side for about 20 seconds to approximately 2000 1 foot candles of white light to expose the top layer.

This exposure may be made through a blue or violet filter. It is then developed in a yellow color-forming developer to produce a positive image 2| of metallic silver and yellow dye in the top layer. A developer suitable for the purpose may have the following composition, the film being developed for about 5 minutes.

Solution A Grams p-Aminodiethylaniline hydrochloride 1 Sodium sulfite 1 Potassium thiocyanate 1 Water to 990 cc.

Solution B Acetoacetanilide grams 10 Sodium hydroxide do 1 Water cc 10 Potassium ferricyanide grams; 50 Ammonium hydroxide 28% cc 2 Potassium bromide grams 5 Water to 1000 cc.

The film is then fixed for about 4 minutes in hypo, washed for several minutes and dried in warm air.

The film then appears as shown in the sixth stage of Fig. 1 with a positive blue-green image 22 in the bottom layer, a positive magenta image is removed by the bleach baths may be used in the filter layer H. We may use a dispersion of colloidal silver, for example. It is also possible, in the practice of certain features of the invention, to use soluble and relatively harmless yellow dyes such as tartrazine and fluorescein which diifuse throughout the film but have a very appreciable screeningaotion'between the top and middle emulsion layers, and which wash out in the first or subsequent developer baths.

In the film which we have described, there may be an anti-halation layer coated on the rear surface of the support in the usual manner, the anti-halation layer'being colored with a material which is decolorized in the processing baths described. The anti-halation layer may also be coated between the support and the sensitive emulsion layer as shown in the modification'of Fig. 2. As shown in Fig. 2, the support I0 carries the usual red; green and blue sensitive layers II, I! and I3 with intermediate layers 25 of gelatin. The anti-halation layer 26 is coated between the support l0 and the red sensitive layer II. It may be comprised of gelatin containing any suitable material which is decolorized in the processing baths, or it may be a layer of nickel sulfide in gelatine which will wash out in a potassium ferricyanide bath. The nickel sulfide antihalation layer may also be coated on the rear surface of the support.

The film and method of process which we have described may be varied in numerous ways, for example, the order of the layers need not be the same as that described above but the red and the green sensitive layers may be reversed, the green sensitive layer being coated adjacent the support. It is also possible to coat the blue sensitive layer adjacent the support and the red and green senitive layers on top of it. In this case, the exposure is made through the support and the yellow filter layer is then coated between the blue sensitive layer and the remaining sensitive layers. It is also possible to vary the order of exposure of the layers in reversingthem. That is, the blue sensitive layer may be exposed and developed first, or before the green sensitive layer, the filter layer protecting the other layers from the blue light, and the green sensitive layer then exposed to green or white light through the combined positive and negative images in the blue sensitive layer. The coupler compounds described need not be in the developer solution but may be contained in one or more of the sensitive layers themselves in the form of known diffusing compounds which couple with the development product of the pphenylenediamine developer on development.

In addition to the color developers described, we may use other p-phenylenediamine and paminophenol developers having free amino groups. In the case of p-phenylenediamine developers, one amino group is preferably substituted with alkyl radicals and the nucleus of the developer may also contain, substituents.

used, such as those described in our U. S. Patents 2,113,330, granted April 5, 1938, 2,108,602, granted February 15, 1938, and 2,039,730, granted May 5, 1936.

Numerous other modifications may be used within the scope of our invention, which is. to be understood as comprising all features coming within the scope of the appended claims.

We claim:

1. The process of producing a colored pho-'v tographic record bycolor-forming development in a sensitive element having three superposed silver halide layers each sensitive to a spectral region different from those to which the other layers are sensitive, which comprises forming latent images in the layers, the images being different color sensation records of a subject, simultaneously developing the latent images to negative metallic silver images, exposing only one of the outer layers from its side of the element to light of a color to which it is sensitive and developing a colored image in it by a color-forming development step, exposing the inner layer through the thus exposed and color-developed outer layer to light of a color to which it is sensitive and developing a colored image in it by a second color-forming development step, exposing the third layer to lightof a color to which it is sensitive and developing a colored image in it by a third color-forming development step, the silver images formed in all development steps remaining in the film at this stage, and removing from the layers the metallic silver images formed in the various development steps.

2. The process of producing a colored photographic record by color-forming development in a sensitive element having three superposed silver halide layers each sensitive to a spectral region different from those to which the other layers are sensitive, which comprises forming latent images in the layers, the images being diiferent color sensation records of a subject, exposing only the layer adjacent the support through the support to light of a color'to which it is sensitive and developing a colored image in it by a color-forming development step, exposing only the middle layer through the thus exposed and color developed layer to light of a color to which it is sensitive and developing a colored image in it by .a second color forming development step, exposing the top layer to light of a color to which it is sensitive and developing a colored image in it by a third color-forming development step, the silver images formed in all development steps remaining in the film at this stage, and removing the metallic silver images from the layers.

3. The process of producing a colored photographic record by color-forming development in a sensitive element having three superposed layers sensitive, in the following order starting from either side of the element, to the blue, green, and red regions of the spectrum, which comprises forming latent images in the layers the Other suitable coupler compounds may also be images being different color sensation records of a subject, simultaneously developing the latent images to negative metallic silver images, exposing only the red sensitive layer from its side of the element to red light and developing a bluegreen image in it by a color-forming development step, exposing only the green sensitive layer through the thus exposed and color developed layer to light of a color to which it is sensitive and developing a magenta image in it by a colorforming development step exposing the blue sensitive layer to light of a color to which it is sensitive and developing a yellow image in it by a color-forming development step, the silver images formed in all development steps remaining in the film at this stage, and removing the metallic silver images from the layers- 4.,The process of producing a colored photographic record by color-forming development in a sensitive element having three superposed layers sensitive, in the following order starting from either side of the element, to the blue, green, and 'red regions of the spectrum, which comprises forming in the three layers by exposure and development three color-component, negative silver images, exposing the red sensitive layer to red light from its side of the element and treating said layer with a color-forming developer yielding an image composed of silver and a blue green dye, exposing only the inner green sensitive layer through the thus exposed and color-developed layer to light to which it is sensitive while protecting the remaining sensitive layer from such light and then treating said exposed layer with a color forming developer yielding an image composed of silver and dye of a color complementary to the color to which said layer was initially sensitive, exposing the third layer to light to which it is sensitive and then treating it with a color-forming developer-yielding an image composed of silver and a dye complementary to the color to which said layer was initially sensitive, the silver images formed in all development steps remaining in the film at this stage, and then removing all of the silver images; leaving three complementary dye images.

5. The process of producing a colored photographic record by color-forming development in a sensitive element having three superposed layers sensitive, in the following order starting from either side of the element, to the blue, green, and red regions of the spectrum, and having between the layers sensitive to the blue and green regions a filter material absorbent of light only in the blue region, and resistant to ordinary developing baths but removable in a bleached bath, which process comprises forming by exposure and development silver color component negative images in the three layers, exposing the red sensitive layer from its side of the element to red light whereby a latent image is formed in the red sensitive layer and developing in said layer by a color forming development step an image composed of silver and a blue green dye, exposing only the inner green sensitive layer through the thus exposed and color developed layer to light to which it is sensitive, the remaining layer being protected by the filter layer from reexposure, developing a silver and dye image in the exposed layer, exposing the remaining layer and developing a color and dye image therein, the silver images formed in all development steps remaining in the film at this stage, and then submitting the element to a bleach bath in which all of the silver images and the filter layer are removed leaving three complementary dye images in the three layers.

6. In the process of producing a multi-color photograhic record in a sensitive element having three superposed layers, each sensitive to a spectral region difierent from those to which the other layers are sensitive, and comprising forming by exposure and development silver negative color component images and by reexposure and color redevelopment positive images of silver and dye and then removing all of the silver images, the steps after the first exposure and development of forming in one of the outer layers by afore mentioned differential color exposure and color redevelopment a combined silver and dye image and then exposing the middle layer to light passing through the developed positive and negative images of the said outer layer.

LEOPOLD D. MANNES. LEOPOLD GODOWSKY, J a. LOT S. WILDER. 

